In a 32-bit environment, sums of 64-bit numbers are typically calculated according to the following algorithm. The least significant thirty-two bits of the first 64-bit number are added to the least significant thirty-two bits of the second 64-bit number. The resulting sum includes a carry (which includes either a one or a zero) and the least significant thirty-two bits of a first 64-bit intermediate sum. The carry and the most significant thirty-two bits of the second 64-bit number are then added to the most significant thirty-two bits of the first 64-bit number, and the resulting sum includes the most significant thirty-two bits of the first 64-bit intermediate sum. The least significant thirty-two bits of the first 64-bit intermediate sum are then added to the least significant thirty-two bits of the third 64-bit number, and the resulting sum includes a carry and the least significant thirty-two bits of a second 64-bit intermediate sum. The carry and the most significant thirty-two bits of the third 64-bit number are then added to the most significant thirty-two bits of the first 64-bit intermediate sum, and the resulting sum includes the most significant thirty-two bits of the second 64-bit intermediate sum. The least significant thirty-two bits of the second 64-bit intermediate sum are then added to the least significant thirty-two bits of the fourth 64-bit number, and the resulting sum includes a carry and the least significant thirty-two bits of a third 64-bit intermediate sum. The carry and the most significant thirty-two bits of the fourth 64-bit number are then added to the most significant thirty-two bits of the second 64-bit intermediate sum, and the resulting sum includes the most significant thirty-two bits of the third 64-bit intermediate sum. This continues until the least and most significant thirty-two bits of the final 64-bit number are added to the least and most significant thirty-two bits of the preceding 64-bit intermediate sum, respectively. The final resulting sums include the least and most significant thirty-two bits of the sum of the 64-bit numbers. A drawback of such an algorithm is that two 32-bit registers are typically required to store the 64-bit intermediate sums, which may adversely affect processor performance and operation efficiency.